Electrostatic machine producing a periodical discharge



g- 3, 1954 M. MENNESSON 2,685,654

ELECTROSTATIC MACHINE PRODUCING A PERIODICAL DISCHARGE Filed Jan. '7,1953 Patented Aug. 3, 1954 ELECTROSTATIC MACPJNE PRODUCING A PERIODICALDISCHARGE Marcel Mennesson, Neuilly-sur- Seine, France, as-

signor to Societe dAppareils de Controle et dEquipement des Moteurs (S.A. C. E. M.), Neuilly-sur-Seine, France, a society of France ApplicationJanuary '7, 1953, Serial No. 330,123

Claims priority, application France January 8, 1952 8 Claims. 1

The present invention relates to electrostatic machines working byinfluence, in particular to rotary machines producing a periodicaldischarge, and it is more especially concerned with internal combustionengine spark ignition machines.

The chief object of my invention is to provide a machine of this kindwhich is better adapted to meet the various requirements of practicethan those existing at the present time.

The machines with which my invention is concerned include at least twoparts in relative movement with respect to each other, one of theseparts carrying an even number of insulated collecting plates initiallyprovided with electricity charges the polarities of which alternate fromone plate to the next one, and the other part carrying a plurality ofinsulated influenced plates, with means for short-circuiting by pairsthe influenced plates, and means for discharging these plates onto thecollecting plates.

They are characterized in that at least one or said means is constitutedboth by combs enabling the electric charges to pass through a thin layerof a gaseous dielectric and by brushes establishing a sliding contact,these brushes being arranged to retract automatically under the actionof a physical force developed by the operation of the machine, when thismachine reaches speed conditions for which electric discharge can beconducted through the combs.

Preferred embodiments of my invention will be hereinafter described withreference to the accompanying drawings, given merely by way of example,and in which:

Fig. l of this drawing diagrammatically shows in cross section a sparkignition machine according to my invention.

Fig. 2 shows a detail of a machine made according to a modification ofthat of Fig. l.

The machine includes at least two portions'in relative movement withrespect to each other, preferably a fixed portion and a rotary portion,one of these portions including an even number of insulated plates(collecting plates), which are supposed initially to carry electriccharges the polarities of which alternate from one plate to the nextone, and the other portion including a plurality of insulated plates(influenced plates) which come successively opposite each of the firstmentioned plates, together with means for successively short-circuitingthe pairs of influenced plates which are opposed with respect to theaxis of the machine, and means for conveying onto the collecting platesthe electric charges which have been generated on the influenced plates.

Concerning the means for successivelyshortcircuiting by pairs the plateswhich have been electrified by influence, and the means for transferringto the collecting plates the charges which have been induced in theinfluenced plates, at least one cf them, and preferably both, includesimultaneously combs (i. e. sharp points) which enable the electriccharges to pass through a thin layer of a gaseous dielectric (of theorder of magnitude of one tenth of a millimetre for instance) andbrushes which establish a sliding contact between the fixed and rotatingplates, and the brushes are arranged in such manner that they retractautomatically, under the effect of a physical force developed by theoperation of the machine, when this operation reaches conditions (and inparticular a rotational speed) such that the transmission of charges cantake place through the combs.

This physical force may be for instance a sue" tion created by theoperation of the machine, but it is more advantageous to use thecentrifugal force developed in elements carried by the rotating portion.

In this case, the brushes are disposed on the rotating portion of themachine and they are arranged in such manner as to be subjected, on theone hand, to the action of this centrifugal force, for instance througha kinematic device (linlr system or other) and, on the other hand, to anantagonistic elastic action.

Preferably, the brushes themselves are subjected to the centrifugalforce and they are given a natural elasticity such that, when themachine rotates at a speed lower than a given value, the brushesestablish a sliding contact with the conducting pieces located oppositethem, whereas, when the machine rotates at a speed higher than thisvalue, the brushes are bent out of contact, the electric charges thenpassing through the combs associated with the brushes.

In the construction shown by the drawing, there are two collectingplates I and 2, charged respectively with negative and positiveelectricity and embedded in an insulating ring s carried by the rotatingportion (rotor) of the machine, the direction of rotation of which isindicated by arrow 1. There is a plurality of influenced platesdiametrically opposed two by two (dclb, 511F512, 6a6b, 'la7b) carried bythe fixed portion (stator) of the machine, constituted by an insulatingmass 8.

According to a first embodiment (Fig. 1), the means for successivelyshort-circuiting the pairs of influenced plates (4a. and 4b, 5a and 5?),etc.)

are constituted by two opposed systems including each a brush (8a, 9b)and a comb (50a, ltb) carried by the rotor and connected by conductormeans. When said conductor means is disposed at the periphery of therotor, the brushes and combs extend through apertures l2a, l2?) providedin ring 3 and. plates l and 2. When the rotor includes a metallicfly-wheel ll, this flywheel may be used as conductor means.

The means for transferring to the collecting plates i, 2 the electriccharges induced in the insulated. plates (ta, lib, etc.) are al oconstituted by two opposed systems including each a brush (53a, ltb) anda comb (Ma, Nib) carried by the rotating plates I, 2.

The brushes (9a, 912, 13a, 1327) are constituted in the embodiment ofFig. l, by bent elastic plates having their convexity turned toward thedirection of rotation, as shown by the drawing.

According to another embodiment (Fig. 2), each comb and brush system isconstituted by a single elastic conductor plate it the edge E of whichplays the part of a comb when, under the effect of the centrifugalforce, plate is is deformed to occupy the position shown in dotted linesin Fig. 2.

The operation of the machine is as follows:

When the machine is started, there is always a difference of polaritybetween plates 2 and 2. As a rule, due to the preceding operation of thenachine, there is always some remaining electricity charges on theseplates, whereby one of them is positively charged with respect to theother. Even without having to rely on the existence of these residualcharges, it is pointed out that rotation of parts li3 with respect tothe stator will produce by friction on air small electric charges, andas these charges are never exactly equal, one or" the plate i2 will becharged more than the other and difiere ces of polarity will thus becreated. For the sake of simplicity, in the following explanations itwill be supposed that plate I is negatively charged and plate 2 ispositively charged. These plates charge by influence the plates (la, 46located respectively opposite them which are shortcircuited throughbrushes 9a and 9b (Fig. 1) or it (Fig. 2) and fly-wheel H. Plate la isthus charged with negative electricity and plate db with positiveelectricity and these plates remain thus charged when, the rotor havingrotated, the connection between them is cut oii. Then, after angulardisplacement of rotor 3, brush H30. comes into contact with plate ta andbrush H32 with plate 4b, whereby the charges carried by plates la and 4bare respectively transferred to collecting plates and 2. Due to therotation of the machine, the charges on the rotating plates 3 and 2 thustend to be multiplied and, when the speed of rotation reaches andexceeds a certain value, these charges are such that communication canbe established through combs it! and i i, (in the case of Fig. l), or It(in the case of Fig. 2) through the gaseous dielectric. this time, underthe effect of the centrifugal force, brushes 9 and [3 (or are bent intothe positions shown in dotted lines where they no longer contact thefixed plates. The operation of the machine remains the same, with theexception that the internal connections are established exclusivelythrough the combs, i. e. without any friction.

According to another feature of my invention, which will be supposed tobe applied to a machine such as that above described for the sparkingignition of internal combustion engines, the rotating portion of themachine is carried by the fly-wheel of the engine, designated by H, saidfiy-wheel is used to constitute one of the armatures of a condenser (themetallic plates I and 2 being for instance surrounded by annularflywheel ii and the insulating ring 3 being interposed between saidfiy-wheel H and said plates l, 2) capable of storing up a certain amountof electricity, and, preferably, the rotor, in particular if it includesa metallic fiy-wheel, is then used as spark distributor.

For this purpose, every second electrifying plate, in particular one ofthe two plates l and 2 in the embodiment shown by the drawing, isprovided with an insulated projection ii extending in an insulatedfashion through the metallic fly-wheel and I dispose externally to therotor a fixed metallic rod I8 in communication with the engine sparkplug, in such manner that at a given time of the rotation of theflywheel, projection li comes opposite'rod l8 and at a small distancethereof. At this time, a short spark is produced between these piecesand causes the spark to be produced at the spark plug: the spark is thusproduced at a time which is in relation with the position of the enginefly-wheel, that is to say with the position of the pi ten (or thepistons) in its cylinder (or their cylinders) I use only every secondplate for the production of the spark, for instance negative plate i. soas to keep the other plate 2 constantly charged with electricity, whichfacilitates the production of electricity in the first plate andobviates risks of failure.

A great advantage of such a machine is that it creates no frictionbetween the contact elements to be connected and, consequently,eliminates the most serious cause of wear and tear of these elements.

In a general manner, while I have, in the above description, disclosedwhat I deem to be practical and efficient embodiments of my invention,it should be well understood that I do not wish to be limited thereto asthere might be changes made in the arrangement, disposition and form ofthe parts without departing from the principle of the present inventionas comprehended within the scope of the accompanying claims.

What I claim is:

1. An electrostatic machine which comprises, in combination, two partsmovable with respect to each other, an even number of insulatedcollecting plates carried by one of said said plates being provided withelectric charges of respective polarities alternating from one plate tothe next one, a plurality of pairs of insulated influenced platescarried by the other part t place the two plates of each pairrespectively opposite two successive collecting plates, means forshort-circuiting said pairs of plates successively, and means fordischarging said influence plates onto said collecting platesrespectively, at least one of said two means including both combs,intended for normal operation of the machine, arranged to pass theelectric charges through a thin layer of a gaseous dielectric, andbrushes, intended for the starting of the machine, arranged to achievesliding contacts for the passage of said charges, said brushes beingretractable into inoperative position in response to a given relativevelocity of said two parts of the machine.

2. An electrostatic machine which comprises, in combination, two partsrotatable with respect to each other, an even number of insulatedcollecting plates carried by one of said parts, said plates beingprovided with electric charges of respective polarities alternating fromone plate to the next one, a plurality of pairs of insulated influencedplates carried by the other part to place the two plates of each pairrespectively opposite two successive collecting plates, means forshort-circuiting said pairs of plates successively, and means fordischarging said influenced plates onto said collecting platesrespectively, at least one of said two means including both combs,intended for normal operation of the machine, arranged to pass theelectric charges through a thin layer of a gaseous dielectric, andbrushes, intended for the starting of the machine, arranged to achievesliding contacts for the passage of said charges, said brushes beingretractable into inoperative position by the centrifugal force developedby one of said parts, which is rotating, When the speed of revolutionthereof reaches a given value.

3. A machine according to claim 2 in which the brushes are elastic anddirectly subjected to the action of the centrifugal force which deformsthem into inactive position.

4. A machine according to claim 2 in which the brushes are constituwd bybent resilient plates carried by the rotating part so as to be deformedinto inoperative position by the centriiugal force.

5. A machine according to claim 4 in which each comb is constituted bythe end of the corresponding brush.

6. A machine according to claim 2 for use as spark ignition machine inconnection with an internal combustion engine, in which the rotatingportion of the machine is carried by the engine fly-Wheel.

7. A machine according to claim 6 in which the fly-wheel constitutes oneof the armatures of a condenser capable of storing up electricity, theother armature being constituted by collecting plates carried by therotating part.

8. An electrostatic machine which comprises, in combination, two partsmovable with respect to each' other, an even number of insulatedcollecting plates carried by one of said parts, said plates beingprovided with electric charges of respective polarities alternating fromone plate to the next one, a plurality of insulated influenced platescarried by the other part so as to be brought successively opposite saidcollecting plate in recurrent fashion, whereby when each of saidinfluenced plates is passing opposite one of said collecting plates, twocharges of equal magnitudes and opposed polarities are formed on theopposed faces thereof respectively by influence from said collectingplate, means responsive to the relative movement of said parts forsuccessively eliminating from every influenced plate as it is stillpassing along each of said collecting plates the electric charge, of thesame polarity as that of said last mentioned collecting plate, which hasbeen formed by influence on the side of said influenced plate opposed tothat facing said collecting plate, and means for discharging saidinfluenced plates onto said collecting plates as soon as they comeopposite them, at least one of said two means including both combs,intended for normal operation of the machine, arranged to pass theelectric charges through a thin layer of a gaseous dielectric, andbrushes, intended for the starting of the machine, arranged to achievesliding contacts for the passage of said charges, said brushes beingretractable into inoperative position in response to a given relativevelocity of said two parts of the machine.

References Cited in the file of this patent FOREIGN PATENTS Number

